I currently have a Dell U3415W monitor. Maximum supported resolution is 3440 x 1440. Radeon additional settings says maximum reported refresh rate is 75 Hz. The monitor is currently running at 60 Hz. When I try to use a custom resolution, I set the refresh rate to 75 Hz, and when verifying, it says the customer resolution settings are not compatible with this display. I'm using the RX 480 card.